The former Ukip leader attacked what he called the “deeply worrying” failure of exit talks to address border controls after a meeting with Michel Barnier.

Mr Farage said Mr Barnier does not understand at all that concern over immigration fuelled the vote to leave, but instead believes the result was down to the promise of extra cash for the NHS.

In a meeting in Brussels, the divisive politician also warned that businesses will push for the Government to walk away from talks if the EU fails to make any concessions on financial services.

He told Sky News: “What he [Barnier] really didn’t understand at all was that open-door immigration within the European Union had been an absolute key driver of all of this.

Nigel Farage at talks in Brussels on Monday (Picture: Rex)

“He really doesn’t see that. The most disappointing thing, if I am speaking on behalf of the 17.4 million, most of them anyway, is that it’s pretty clear that in the talks that have happened so far immigration, frankly, hasn’t even been discussed.